Using zeolite SSZ-58 for reduction of oxides of nitrogen in a gas stream

ABSTRACT

The present invention relates to new crystalline zeolite SSZ-58 and processes employing SSZ-58 as a catalyst.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to new crystalline zeolite SSZ-58 andprocesses employing SSZ-58 as a catalyst.

2. State of the Art

Because of their unique sieving characteristics, as well as theircatalytic properties, crystalline molecular sieves and zeolites areespecially useful in applications such as hydrocarbon conversion, gasdrying and separation. Although many different crystalline molecularsieves have been disclosed, there is a continuing need for new zeoliteswith desirable properties for gas separation and drying, hydrocarbon andchemical conversions, and other applications. New zeolites may containnovel internal pore architectures, providing enhanced selectivities inthese processes.

Crystalline aluminosilicates are usually prepared from aqueous reactionmixtures containing alkali or alkaline earth metal oxides, silica, andalumina. Crystalline borosilicates are usually prepared under similarreaction conditions except that boron is used in place of aluminum. Byvarying the synthesis conditions and the composition of the reactionmixture, different zeolites can often be formed.

SUMMARY OF THE INVENTION

The present invention is directed to a family of crystalline molecularsieves with unique properties, referred to herein as “zeolite SSZ-58” orsimply “SSZ-58”. Preferably, SSZ-58 is obtained in its silicate,aluminosilicate, titanosilicate, vanadosilicate or borosilicate form.The term “silicate” refers to a zeolite having a high mole ratio ofsilicon oxide relative to aluminum oxide, preferably a mole ratiogreater than 100, including zeolites comprised entirely of siliconoxide. As used herein, the term “aluminosilicate” refers to a zeolitecontaining both alumina and silica and the term “borosilicate” refers toa zeolite containing oxides of both boron and silicon.

In accordance with the present invention, there is provided an improvedprocess for the reduction of oxides of nitrogen contained in a gasstream in the presence of oxygen wherein said process comprisescontacting the gas stream with a zeolite, the improvement comprisingusing as the zeolite a zeolite having a mole ratio greater than about 20of an oxide of a first tetravalent element to an oxide of a secondtetravalent element different from said first tetravalent element,trivalent element, pentavalent element or mixture thereof and having,after calcination, the X-ray diffraction lines of Table II. The zeolitemay contain a metal or metal ions (such as cobalt, copper or mixturesthereof) capable of catalyzing the reduction of the oxides of nitrogen,and may be conducted in the presence of a stoichiometric excess ofoxygen. In a preferred embodiment, the gas stream is the exhaust streamof an internal combustion engine.

DETAILED DESCRIPTION OF THE INVENTION

The present invention comprises a family of crystalline, zeolitesdesignated herein “zeolite SSZ-58” or simply “SSZ-58”. SSZ-58 isbelieved to be a large pore zeolite. As used herein, the term “largepore” means having an average pore size diameter greater than about 6.5Angstroms, preferably from about 7 Angstroms to about 8 Angstroms.

In preparing SSZ-58 zeolites, a N-butyl-N-cyclooctylpyrrolidinium cationor N-propyl-cyclooctylpyrrolidinium cation is used as a crystallizationtemplate. In general, SSZ-58 is prepared by contacting an active sourceof one or more oxides selected from the group consisting of monovalentelement oxides, divalent element oxides, trivalent element oxides, andtetravalent element oxides with the templating agent.

SSZ-58 is prepared from a reaction mixture having the composition shownin Table A below.

TABLE A Reaction Mixture Typical Preferred YO₂/W_(a)O_(b) >20 35-65OH—/YO₂ 0.10-0.50 0.15-0.25 Q/YO₂ 0.05-0.50 0.10-0.20 M_(2/n)/YO₂0.02-0.40 0.10-0.30 H₂O/YO₂  25-100 30-50

wherein Y is silicon, germanium or a mixture thereof; W is aluminum,gallium, iron, boron, titanium, indium, vanadium or mixtures thereof; Mis an alkali metal cation, alkaline earth metal cation or mixturesthereof; n is the valence of M (i.e., 1 or 2); Q is aN-butyl-N-cyclooctylpyrrolidinium cation orN-propyl-cyclooctylpyrrolidinium cation., and a is 1 or 2, and b is 2when a is 1 (i.e., W is tetravalent) and b is 3 when a is 2 (i.e., W istrivalent).

In practice, SSZ-58 is prepared by a process comprising:

(a) preparing an aqueous solution containing sources of at least oneoxide capable of forming a crystalline molecular sieve and aN-butyl-N-cyclooctylpyrrolidinium cation orN-propyl-cyclooctylpyrrolidinium cation having an anionic counterionwhich is not detrimental to the formation of SSZ-58;

(b) maintaining the aqueous solution under conditions sufficient to formcrystals of SSZ-58; and

(c) recovering the crystals of SSZ-58.

Accordingly, SSZ-58 may comprise the crystalline material and thetemplating agent in combination with metallic and non-metallic oxidesbonded in tetrahedral coordination through shared oxygen atoms to form across-linked three dimensional crystal structure. The metallic andnon-metallic oxides comprise one or a combination of oxides of a firsttetravalent element(s), and one or a combination of a second tetravalentelement(s) different from the first tetravalent element(s), trivalentelement(s), pentavalent element(s) or mixture thereof. The firsttetravalent element(s) is preferably selected from the group consistingof silicon, germanium and combinations thereof. More preferably, thefirst tetravalent element is silicon. The second tetravalent element(which is different from the first tetravalent element), trivalentelement and pentavalent element is preferably selected from the groupconsisting of aluminum, gallium, iron, boron, titanium, indium, vanadiumand combinations thereof. More preferably, the second trivalent ortetravalent element is aluminum or boron.

Typical sources of aluminum oxide for the reaction mixture includealuminates, alumina, aluminum colloids, aluminum oxide coated on silicasol, hydrated alumina gels such as Al(OH)₃ and aluminum compounds suchas AlCl₃ and Al₂(SO₄)₃. Typical sources of silicon oxide includesilicates, silica hydrogel, silicic acid, fumed silica, colloidalsilica, tetra-alkyl orthosilicates, and silica hydroxides. Boron, aswell as gallium, germanium, titanium, indium, vanadium and iron, can beadded in forms corresponding to their aluminum and silicon counterparts.

A source zeolite reagent may provide a source of aluminum or boron. Inmost cases, the source zeolite also provides a source of silica. Thesource zeolite in its dealuminated or deboronated form may also be usedas a source of silica, with additional silicon added using, for example,the conventional sources listed above. Use of a source zeolite reagentas a source of alumina for the present process is more completelydescribed in U.S. Pat. No. 5,225,179, issued Jul. 6, 1993 to Nakagawaentitled “Method of Making Molecular Sieves”, the disclosure of which isincorporated herein by reference.

Typically, an alkali metal hydroxide and/or an alkaline earth metalhydroxide, such as the hydroxide of sodium, potassium, lithium, cesium,rubidium, calcium, and magnesium, is used in the reaction mixture;however, this component can be omitted so long as the equivalentbasicity is maintained. The templating agent may be used to providehydroxide ion. Thus, it may be beneficial to ion exchange, for example,the halide for hydroxide ion, thereby reducing or eliminating the alkalimetal hydroxide quantity required. The alkali metal cation or alkalineearth cation may be part of the as-synthesized crystalline oxidematerial, in order to balance valence electron charges therein.

The reaction mixture is maintained at an elevated temperature until thecrystals of the SSZ-58 zeolite are formed. The hydrothermalcrystallization is usually conducted under autogenous pressure, at atemperature between 100° C. and 200° C., preferably between 135° C. and160° C. The crystallization period is typically greater than 1 day andpreferably from about 3 days to about 20 days.

Preferably, the zeolite is prepared using mild stirring or agitation.

During the hydrothermal crystallization step, the SSZ-58 crystals can beallowed to nucleate spontaneously from the reaction mixture. The use ofSSZ-58 crystals as seed material can be advantageous in decreasing thetime necessary for complete crystallization to occur. In addition,seeding can lead to an increased purity of the product obtained bypromoting the nucleation and/or formation of SSZ-58 over any undesiredphases. When used as seeds, SSZ-58 crystals are added in an amountbetween 0.1 and 10% of the weight of silica used in the reactionmixture.

Once the zeolite crystals have formed, the solid product is separatedfrom the reaction mixture by standard mechanical separation techniquessuch as filtration. The crystals are water-washed and then dried, e.g.,at 90° C. to 150° C. for from 8 to 24 hours, to obtain theas-synthesized SSZ-58 zeolite crystals. The drying step can be performedat atmospheric pressure or under vacuum.

SSZ-58 as prepared has a mole ratio of an oxide selected from siliconoxide, germanium oxide and mixtures thereof to an oxide selected fromaluminum oxide, gallium oxide, iron oxide, boron oxide, titanium oxide,indium oxide, vanadium oxide and mixtures thereof greater than about 20;and has, after calcination, the X-ray diffraction lines of Table IIbelow. SSZ-58 further has a composition, as synthesized (i.e., prior toremoval of the templating agent from the zeolite) and in the anhydrousstate, in terms of mole ratios, shown in Table B below.

TABLE B As-Synthesized SSZ-58 YO_(2/W) _(c)O_(d) >20 M_(2/n)/YO₂0.01-0.03 Q/YO₂ 0.02-0.05

where Y, W, n, M and Q are as defined above and c is 1 or 2; d is 2 whenc is 1 (i.e., W is tetravalent) or d is 3 or 5 when c is 2 (i.e., d is 3when W is trivalent or 5 when W is pentavalent).

SSZ-58 can be made essentially aluminum free, i.e., having a silica toalumina mole ratio of ∞. A method of increasing the mole ratio of silicato alumina is by using standard acid leaching or chelating treatments.However, essentially aluminum-free SSZ-58 can be synthesized directlyusing essentially aluminum-free silicon sources as the main tetrahedralmetal oxide component, if boron is also present. SSZ-58 can also beprepared directly as either an aluminosilicate or a borosilicate.

Lower silica to alumina ratios may also be obtained by using methodswhich insert aluminum into the crystalline framework. For example,aluminum insertion may occur by thermal treatment of the zeolite incombination with an alumina binder or dissolved source of alumina. Suchprocedures are described in U.S. Pat. No. 4,559,315, issued on Dec. 17,1985 to Chang et al.

It is believed that SSZ-58 is comprised of a new framework structure ortopology which is characterized by its X-ray diffraction pattern. SSZ-58zeolites, as-synthesized, have a crystalline structure whose X-raypowder diffraction pattern exhibit the characteristic lines shown inTable I and is thereby distinguished from other zeolites.

TABLE I As Synthesized SSZ-58 2 Theta (deg.)^((a)) d RelativeIntensity^((b)) 7.1 12.4 S 7.7 11.5 M 9.9 8.93 M 10.5 8.42 W 12.1 7.31 M17.3 5.12 W 19.7 4.50 M 21.0 4.23 S 21.9 4.06 M 22.35 3.97 VS^((a))±0.15^((b) The X-ray patterns provided are based on a relative intensity scale in which the strongest line in the X-ray pattern is assigned a value of 100: W(weak) is less than 20; M(medium) is between 20 and 40; S(strong) is between 40 and 60; VS(very strong) is greater than 60.)

Table IA below shows the X-ray powder diffraction lines foras-synthesized SSZ-58 including actual relative intensities.

TABLE IA As-Synthesized SSZ-58 2 Theta (deg)^((a)) d I/I₀ × 100 6.90 12.80 (Sh) 6 7.06 12.51  39 7.72 1.44  16 9.86   8.963 (Sh) 10 9.968.874 13 10.46 8.450 10 12.10 7.309 18 14.06 6.294 9 14.21   6.228 (Sh)7 15.46 5.727 5 15.68 5.647 6 16.12 5.494 4 17.24 5.139 14 17.36   5.104(Sh) 7 18.76 4.726 15 18.92 4.687 16 19.72 4.498 30 20.22 4.388 14 20.704.288 16 21.00 4.227 63 21.16 4.195 14 21.26   4.176 (Sh) 12 21.88 4.05926 22.28   3.987 (Sh) 61 22.24 3.962 100 22.66 3.921 26 23.02 3.860 923.28 3.818 5 23.50 3.783 17 23.68 3.754 13 24.34 3.654 5 25.12 3.542 1125.54 3.485 7 25.72   3.461 (Sh) 4 26.12 3.409 8 26.58 3.351 7 27.303.264 11 27.58 3.232 7 27.94 3.191 5 28.50   3.129 (Sh) 8 28.62 3.117 1129.18 3.058 2 29.86 2.990 5 30.08 2.968 5 30.88 2.894 3 31.46 2.842 231.74 2.817 4 32.48 2.755 1 32.59 2.746 2 32.76 2.732 3 33.14 2.701 433.56 2.668 3 33.80 2.650 2 34.82 2.574 2 35.12 2.553 1 35.38 2.535 335.82 2.505 6 36.50 2.460 6 37.74 2.382 4 37.94   2.370 (Sh) 2 38.442.340 2 39.29 2.291 2 39.62 2.273 1 41.10 2.194 1 43.12 2.096 2 43.302.086 5 43.50 2.079 2 ^((a))±0.15

After calcination, the SSZ-58 zeolites have a crystalline structurewhose X-ray powder diffraction pattern include the characteristic linesshown in Table II:

TABLE II Calcined SSZ-58 2 Theta (deg.)^((a)) d Relative Intensity 7.112.4 VS 7.7 11.5 M 9.9 8.93 M 10.5 8.42 M 12.1 7.31 W 17.3 5.12 W 19.84.48 M 21.0 4.23 S 21.9 4.06 M 22.4 3.97 S ^((a))±0.15

Table IIA below shows the X-ray powder diffraction lines for calcinedSSZ-58 including actual relative intensities.

TABLE IIA Calcined SSZ-58 Two Theta (deg.)^((a)) d I/Io × 100 6.88 12.84 (Sh) 17 7.06 12.51  100 7.70 11.47  22 9.86   8.963 (Sh) 20 9.988.856 35 10.48 8.435 15 12.12 7.297 9 14.20 6.232 11 15.48 5.720 6 15.705.640 10 15.84 5.590 7 16.14 5.487 6 17.24 5.139 11 17.37 5.101 4 18.784.721 7 18.96 4.677 14 19.76 4.489 23 20.26 4.380 8 20.70 4.287 13 21.024.223 40 21.22   4.184 (Sh) 9 21.90 4.055 18 22.35   3.975 (Sh) 39 22.463.955 64 22.70 3.914 18 23.04 3.857 3 23.28 3.818 3 23.54 3.776 13 23.743.745 8 24.38 3.648 3 25.16 3.537 8 25.60 3.477 5 25.78   3.453 (Sh) 426.14 3.406 5 26.64 3.343 6 27.34 3.259 6 27.64 3.225 6 27.98 3.186 428.58   3.121 (Sh) 7 28.68 3.110 8 29.20 3.056 1 29.88 2.988 4 30.192.958 3 30.92 2.890 2 31.48 2.840 2 31.74 2.817 3 32.54 2.750 1 32.762.731 1 33.18 2.698 2 33.62 2.664 2 33.86 2.645 2 34.88 2.570 1 35.202.548 1 35.42 2.532 2 35.90 2.499 5 36.54 2.457 4 37.80 2.378 3 38.00  2.366 (Sh) 2 38.50 2.336 1 39.30 2.291 1 43.20 2.092 2 43.42 2.082 443.53 2.077 3

The X-ray powder diffraction patterns were determined by standardtechniques. The radiation was the K-alpha/doublet of copper. The peakheights and the positions, as a function of 2θ where θ is the Braggangle, were read from the relative intensities of the peaks, and d, theinterplanar spacing in Angstroms corresponding to the recorded lines,can be calculated.

The variation in the scattering angle (two theta) measurements, due toinstrument error and to differences between individual samples, isestimated at ±0.20 degrees.

The X-ray diffraction pattern of Table I is representative of“as-synthesized” or “as-made” SSZ-58 zeolites. Minor variations in thediffraction pattern can result from variations in the silica-to-aluminaor silica-to-boron mole ratio of the particular sample due to changes inlattice constants. In addition, sufficiently small crystals will affectthe shape and intensity of peaks, leading to significant peakbroadening.

Representative peaks from the X-ray diffraction pattern of calcinedSSZ-58 are shown in Table II. Calcination can also result in changes inthe intensities of the peaks as compared to patterns of the “as-made”material, as well as minor shifts in the diffraction pattern. Thezeolite produced by exchanging the metal or other cations present in thezeolite with various other cations (such as H⁺ or NH₄ ⁺) yieldsessentially the same diffraction pattern, although again, there may beminor shifts in the interplanar spacing and variations in the relativeintensities of the peaks. Notwithstanding these minor perturbations, thebasic crystal lattice remains unchanged by these treatments.

Crystalline SSZ-58 can be used as-synthesized, but preferably will bethermally treated (calcined). Usually, it is desirable to remove thealkali metal cation by ion exchange and replace it with hydrogen,ammonium, or any desired metal ion. The zeolite can be leached withchelating agents, e.g., EDTA or dilute acid solutions, to increase thesilica to alumina mole ratio. The zeolite can also be steamed; steaminghelps stabilize the crystalline lattice to attack from acids.

The zeolite can be used in intimate combination with hydrogenatingcomponents, such as tungsten, vanadium molybdenum, rhenium, nickelcobalt, chromium, manganese, or a noble metal, such as palladium orplatinum, for those applications in which ahydrogenation-dehydrogenation function is desired.

Metals may also be introduced into the zeolite by replacing some of thecations in the zeolite with metal cations via standard ion exchangetechniques (see, for example, U.S. Pat. No. 3,140,249 issued Jul. 7,1964 to Plank et al.; U.S. Pat. No. 3,140,251 issued Jul. 7, 1964 toPlank et al.; and U.S. Pat. No. 3,140,253 issued Jul. 7, 1964 to Planket al.). Typical replacing cations can include metal cations, e.g., rareearth, Group IA, Group IIA and Group VIII metals, as well as theirmixtures. Of the replacing metallic cations, cations of metals such asrare earth, Mn, Ca, Mg, Zn, Cd, Pt, Pd, Ni, Co, Ti, Al, Sn, and Fe areparticularly preferred.

The hydrogen, ammonium, and metal components can be ion-exchanged intothe SSZ-58. The zeolite can also be impregnated with the metals, or, themetals can be physically and intimately admixed with the zeolite usingstandard methods known to the art.

Typical ion-exchange techniques involve contacting the synthetic zeolitewith a solution containing a salt of the desired replacing cation orcations. Although a wide variety of salts can be employed, chlorides andother halides, acetates, nitrates, and sulfates are particularlypreferred. The zeolite is usually calcined prior to the ion-exchangeprocedure to remove the organic matter present in the channels and onthe surface, since this results in a more effective ion exchange.Representative ion exchange techniques are disclosed in a wide varietyof patents including U.S. Pat. No. 3,140,249 issued on Jul. 7, 1964 toPlank et al.; U.S. Pat. No. 3,140,251 issued on Jul. 7, 1964 to Plank etal.; and U.S. Pat. No. 3,140,253 issued on Jul. 7, 1964 to Plank et al.

Following contact with the salt solution of the desired replacingcation, the zeolite is typically washed with water and dried attemperatures ranging from 65° C. to about 200° C. After washing, thezeolite can be calcined in air or inert gas at temperatures ranging fromabout 200° C. to about 800° C. for periods of time ranging from 1 to 48hours, or more, to produce a catalytically active product especiallyuseful in hydrocarbon conversion processes.

Regardless of the cations present in the synthesized form of SSZ-58, thespatial arrangement of the atoms which form the basic crystal lattice ofthe zeolite remains essentially unchanged.

SSZ-58 can be formed into a wide variety of physical shapes. Generallyspeaking, the zeolite can be in the form of a powder, a granule, or amolded product, such as extrudate having a particle size sufficient topass through a 2-mesh (Tyler) screen and be retained on a 400-mesh(Tyler) screen. In cases where the catalyst is molded, such as byextrusion with an organic binder, the aluminosilicate can be extrudedbefore drying, or, dried or partially dried and then extruded.

SSZ-58 can be composited with other materials resistant to thetemperatures and other conditions employed in organic conversionprocesses. Such matrix materials include active and inactive materialsand synthetic or naturally occurring zeolites as well as inorganicmaterials such as clays, silica and metal oxides. Examples of suchmaterials and the manner in which they can be used are disclosed in U.S.Pat. No. 4,910,006, issued May 20, 1990 to Zones et al., and U.S. Pat.No. 5,316,753, issued May 31, 1994 to Nakagawa, both of which areincorporated by reference herein in their entirety.

SSZ-58 may be used for the catalytic reduction of the oxides of nitrogenin a gas stream. Typically, the gas stream also contains oxygen, often astoichiometric excess thereof. Also, the SSZ-58 may contain a metal ormetal ions within or on it which are capable of catalyzing the reductionof the nitrogen oxides. Examples of such metals or metal ions includecopper, cobalt and mixtures thereof.

One example of such a process for the catalytic reduction of oxides ofnitrogen in the presence of a zeolite is disclosed in U.S. Pat. No.4,297,328, issued Oct. 27, 1981 to Ritscher et al., which isincorporated by reference herein. There, the catalytic process is thecombustion of carbon monoxide and hydrocarbons and the catalyticreduction of the oxides of nitrogen contained in a gas stream, such asthe exhaust gas from an internal combustion engine. The zeolite used ismetal ion-exchanged, doped or loaded sufficiently so as to provide aneffective amount of catalytic copper metal or copper ions within or onthe zeolite. In addition, the process is conducted in an excess ofoxidant, e.g., oxygen.

EXAMPLES

The following examples demonstrate but do not limit the presentinvention. The templating agent indicated Table C below is used in theseexamples.

TABLE C

The anion (X⁻) associated with the cation may be any anion which is notdetrimental to the formation of the zeolite. Representative anionsinclude halogen, e.g., fluoride, chloride, bromide and iodide,hydroxide, acetate, sulfate, tetrafluoroborate, carboxylate, and thelike. Hydroxide is the most preferred anion.

Example 1 Synthesis of N-butyl-N-cyclooctylpyrrolidinium hydroxide(Template A) I. Synthesis of N-cyclooctylpyrrolidine

A three-neck 3000 ml. flask was charged with 75 gm. (1.05 moles) ofpyrrolidine, 51 gm. cyclooctanone (0.4 mole) and 80 ml. anhydroushexane. To the resulting solution, 80 gm. (0.8 mole) of anhydrousmagnesium sulfate was added and the mixture was mechanically stirred andheated at reflux (the reaction was monitored by NMR analysis) for 108hours. The reaction mixture was filtered through a fritted glass funnel.The filtrate was concentrated at reduced pressure on a rotary evaporatorto give 70.5 gm. of a clear (yellow-tinted) oily substance. ¹H-NMR and¹³C-NMR spectra were acceptable for the desired product,1-(1-pyrrolino)cyclooctene. Saturation of the 1-(1-pyrrolino)cycloocteneto give N-cyclooctylpyrrolidine was accomplished in 98% yield bycatalytic hydrogenation in ethanol at a 55 psi pressure of hydrogen gasin the presence of 10% Pd on activated carbon.

II. Quaternization (synthesis of N-butyl-N-cyclooctylpyrrolidiniumiodide)

To a solution of 60 gms. (0.33 mole) of N-cyclooctyl pyrrolidine in 600ml. anhydrous methanol, 150 gm. (0.825 mole) of butyl iodide was added.The reaction mixture was refluxed while stirring for four days. Then anadditional equivalent of butyl iodide and one equivalent (33 gm., 0.33mole) of potassium bicarbonate were added and the mixture was stirred atrefluxing temperature for an additional 36 hours. The reaction mixturewas concentrated at reduced pressure on a rotary evaporator to give anoff-white colored solid material. The solids were rinsed several timeswith chloroform and filtered after each rinse. All the chloroform rinseswere combined and concentrated to give a white powder whose NMR datawere acceptable for the desired quaternary ammonium iodide salt. Thereaction afforded 109 gm. (90% yield) ofN-butyl-N-cyclooctylpyrrolidinium iodide. The iodide salt was purifiedby recrystallization by completely dissolving the iodide salt inacetone, and then precipitating by the addition of ethyl ether to theacetone solution. This procedure gave 98 gms. of white powder with veryclean ¹H and ¹³C-NRM spectra.

III. Ion Exchange (synthesis of N-butyl-N-cyclooctylpyrrolidiniumhydroxide)

N-butyl-N-cyclooctylpyrrolidinium iodide salt (95 gms., 0.26 mole) wasdissolved in 300 ml. water in a 1000 ml. plastic bottle. To thesolution, 300 gms. of Ion Exchange Resin OH (BIO RAD® AG1-X8) was addedand the mixture was stirred at room temperature overnight. The mixturewas filtered and the solids were rinsed with an additional 250 ml. ofwater. The original mixture was filtered and the rinse were combined anda small amount was titrated with 0.1N HCl to indicate the presence of0.24 mol hydroxide (0.24 mol N-butyl-N-cyclooctylpyrrolidiniumhydroxide) in the solution.

The synthetic procedure described above is depicted below.

In a manner similar to that of Example 1,N-propyl-cyclooctylpyrrolidinium cation (Template B) can be prepared.

Example 2 Preparation of Borosilicate SSZ-58

A 23 cc. Teflon liner was charged with 6.9 gms. of 0.435M aqueoussolution of N-butyl-N-cyclooctylpyrrolidinium hydroxide (3 mmol,Template A), 1.2 gms. of 1M aqueous solution of NaOH (1.2 mmol NaOH) and3.9 gms. of deionized water. To the resulting mixture, 0.06 gm. ofsodium borate decahydrate (0.157 mmol of sodium borate decahydrate,about 0.315 mmol B₂O₃) was added and stirred until completely dissolved.Then 0.9 gm. of Cabosil-M-5 fumed SiO₂ (about 14.7 mmol SiO₂) was addedto the solution and the mixture was thoroughly stirred. The resultinggel was capped off and placed in a Parr bomb steel reactor and heated inan oven at 160° C. while rotating at 43 rpm. The reaction was monitoredby checking the gel's pH, and by looking for crystal formation usingScanning Electron Microscopy (SEM) at six day intervals. The reactionwas completed after heating for 12 days at the conditions describedabove. Once the crystallization was complete, the starting reaction gelturned to a mixture comprising a clear liquid layer with solids (powder)that settled to the bottom. The mixture was filtered through a frittedglass funnel. The collected solids were thoroughly washed with water andthen rinsed with acetone (10 ml.) to remove any organic residues. Thesolids were allowed to air-dry overnight and then they were oven-driedat 120° C. for one hour. The reaction afforded 0.78 gm. of a very finepowder. SEM showed the presence of only one crystalline phase. The X-rayanalysis of the powder indicated that the material was SSZ-58.

Examples 3-16 Synthesis of Borosilicate SSZ-58

The synthesis of Example 1 was repeated keeping the amount of NaOH,water and Cab-OSil M5 the same while varying the amount of Na₂B₄O₇10H₂O.The SiO₂/OH mole ratio was 3.5, the H₂O/SiO₂mole ratio was 45 and theSiO₂/B₂O₃ and SiO₂/Na mole ratios were as indicated in the table below.The reactions were carried out at 160° C. and 43 rpm.

Example No. SiO₂/B₂O₃ SiO₂/Na Days Products 3 280 11.74 12 SSZ-58 4 14011.26 12 SSZ-58 5 93.6 10.83 12 SSZ-58 6 70 10.42 12 SSZ-58 7 56 10.0512 SSZ-58 8 46.3 9.7 12 SSZ-58 9 40 9.38 12 SSZ-58 10 35 9.07 12 SSZ-5811 31 8.8 18 SSZ-58 12 28 8.52 18 SSZ-58 + layered mat'l 13 25.5 8.27 18SSZ-58 + layered mat'l 14 23.3 8.03 18 SSZ-58 (major) + layered mat'l(minor) 15 21.55 7.81 18 SSZ-58 (major) + layered mat'l (minor) 16 18.677.4 21 SSZ-58 + layered mat'l (minor)

Example 17 Synthesis of Aluminosilicate SSZ-58

A 23 cc. Teflon liner was charged with 5.2 gms. of 0.435M aqueoussolution of N-butyl-N-cyclooctylpyrrolidinium hydroxide (2.25 mmolTemplate A), 1.5 gms. of 1M NaOH aqueous solution (1.5 mmol NaOH) and0.75 gm. of deionized water. To the resulting solution, 0.25 gm. ofsodium-Y zeolite (Union Carbide LZ-Y52: SiO₂/Al₂O₃=5) and 0.80 gm. ofCabosil M-5 fumed SiO₂ (about 13 mmol SiO₂) was added, consecutively.The resulting mixture was thoroughly stirred and the resulting gel wascapped off and placed in a Parr bomb steel reactor and heated in an ovenat 160° C. while rotating at 43 rpm. The reaction was monitored bychecking the gel's pH, and by looking for crystal formation using SEM atsix day intervals. The reaction was completed after heating at theconditions described above for six days. The completed reaction mixtureappeared as a colorless liquid with fine white solid settled to thebottom of the Teflon liner. The mixture was filtered through a frittedglass funnel, and the obtained white solids were washed generously withwater and then rinsed with a small amount of acetone and allowed toair-dry overnight. The solids were further dried in an oven at 120° C.for one hour. The reaction yielded 0.81 gm. of SSZ-58.

Examples 18-32 Synthesis of Aluminosilicate SSZ-58

The synthesis of Example 17 was repeated using LZ-Y52 as the aluminumsource and Cab-O-Sil M5 as the SiO₂ source. The SiO₂/OH mole ratio was8.7, the H₂O/SiO₂mole ratio was 28 and the SiO₂/Al₂O₃ and SiO₂/Na moleratios were as indicated in the table below. The reactions were carriedout at 160° C. and 43 rpm.

Example No. SiO₂/Al₂O₃ SiO₂/Na Products 18 317 8.4 SSZ-58 + Trace LZ-Y5219 158.5 8.1 SSZ-58 + Trace LZ-Y52 20 107.5 7.78 SSZ-58 + Trace LZ-Y5221 82.5 7.5 SSZ-58 22 66.9 7.3 SSZ-58 23 56.5 7.1 SSZ-58 24 49 6.9SSZ-58 25 43.5 6.7 SSZ-58 26 39 6.6 SSZ-58 + trace LZ-Y52 27 35.8 6.4SSZ-58 + trace LZ-Y52 28 33 6.26 SSZ-58 (mostly) + LZ-Y52 29 30.8 6.16SSZ-58 (mostly) + LZ-Y52 30 26.3 5.85 SSZ-58 (major) LZ-Y52 (minor) 3123.8 5.66 SSZ-58 (major) LZ-Y52 (minor) 32 20 5.32 SSZ-58 (major) LZ-Y52(minor)

Example 33 Synthesis of All-Silica SSZ-58

A 23 cc. Teflon liner was charged with 6.9 gms. of 0.435M aqueoussolution of N-butyl-N-cyclooctylpyrrolidinium hydroxide (3 mmol TemplateA), 1.2 gms. of 1M NaOH aqueous solution (1.2 mmol NaOH) and 3.9 gm. ofdeionized water. To the resulting solution, 0.9 gm. of Cabosil M-5 fumedSiO2 (about 14.7 mmol SiO₂) was added and the mixture was thoroughlystirred. The resulting mixture was thoroughly stirred and the resultinggel was capped off and placed in a Parr bomb steel reactor and heated inan oven at 160° C. while rotating at 43 rpm. The reaction was monitoredby checking the gel's pH, and by looking for crystal formation using SEMat six day intervals. The reaction was completed after heating at theconditions described above for 18 days. The completed reaction mixtureappeared as a colorless liquid with solids (powder) settled to thebottom of the Teflon liner. The mixture was filtered through a frittedglass funnel. The collected solids were thoroughly washed with water andthen rinsed with acetone (10 ml.) to remove any organic residues. Thesolids were allowed to air-dry overnight and then dried in an oven at120° C. for one hour. The reaction yielded 0.73 gm. of pure SSZ-58

Example 34 Seeded Synthesis of Borosilicate SSZ-58

A 23 cc Teflon liner is charged with 6.9 gm of 0.435M aqueous solutionof N-butyl-N-cyclooctylpyrrolidinium hydroxide (3 mmol template), 1.2 gmof 1M aqueous solution of NaOH (1.2 mmol NaOH) and 3.9 gm of de-ionizedwater. To this mixture, 0.06 gm of sodium borate decahydrate (0.157 mmolof Na₂B₄O₇. 10H₂O;˜0.315 mmol B₂O₃) is added and stirred untilcompletely dissolved. Then, 0.9 gm of CABOSIL-M-5 (˜14.7 mmol SiO₂) and0.04 gm of SSZ-58 (the product of Example 1) is added to the solutionand the mixture is thoroughly stirred. The resulting gel is capped offand placed in a Parr bomb steel reactor and heated in an oven at 160° C.while rotating at 43 rpm. The reaction is monitored by checking thegel's pH, and by looking for crystal formation using Scanning ElectronMicroscopy (SEM). The reaction is completed after heating for 5 days atthe conditions described above. Once the crystallization is complete,the starting reaction gel turns to a mixture comprising of a clearliquid layer with solids (powder) that settled to the bottom. Themixture is filtered through a fitted-glass funnel. The collected solidsare thoroughly washed with water and, then, rinsed with acetone (10 ml)to remove any organic residues. The solids are allowed to air-dry overnight and, then, dried in an oven at 120° C. for one hour. The reactionaffords 0.85 gram of a very fine powder. SEM shows the presence of onlyone crystalline phase. The X-ray pattern of the powder is identical tothe XRD pattern of the product of Example 1.

Example 35 Calcination of SSZ-58

The material from Example 2 is calcined in the following manner. A thinbed of material is heated in a muffle furnace from room temperature to120° C. at a rate of 1° C. per minute and held at 120° C. for threehours. The temperature is then ramped up to 540° C. at the same rate andheld at this temperature for 5 hours, after which it is increased to594° C. and held there for another 5 hours. A 50/50 mixture of air andnitrogen is passed over the zeolite at a rate of 20 standard cubic feetper minute during heating. The product had the X-ray diffraction dataTable IIA above.

Example 36 NH₄Exchange

Ion exchange of calcined SSZ-58 material (prepared in Example 35) isperformed using NH₄NO₃ to convert the zeolite from its Na⁺ form to theNH⁺ form, and, ultimately, the H⁺ form. Typically, the same mass ofNH₄NO₃ as zeolite is slurried in water at a ratio of 25-50:1 water tozeolite. The exchange solution is heated at 95° C. for 2 hours and thenfiltered. This procedure can be repeated up to three times. Followingthe final exchange, the zeolite is washed several times with water anddried. This NH₄ ⁺ form of SSZ-58 can then be converted to the H⁺ form bycalcination (as described in Example 35) to 540° C.

Example 37 Constraint Index Determination

The hydrogen form of the zeolite of Example 17 (after treatmentaccording to Examples 34 and 35) is pelletized at 2-3 KPSI, crushed andmeshed to 20-40, and then>0.50 gram is calcined at about 540° C. in airfor four hours and cooled in a desiccator. 0.50 Gram is packed into a ⅜inch stainless steel tube with aluminum on both sides of the zeolitebed. A Lindburg furnace is used to heat the reactor tube. Helium isintroduced into the reactor tube at 10 cc/min. and at atmosphericpressure. The reactor is heated to about 315° C., and a 50/50 (w/w) feedof n-hexane and 3-methylpentane is introduced into the reactor at a rateof 8 μl/min. Feed delivery is made via an ISCO pump. Direct samplinginto a gas chromatograph begins after 10 minutes of feed introduction.The Constraint Index value is calculated from the gas chromatographicdata using methods known in the art, and is found to be 0.57. At 315° C.and 10 minutes on-stream, feed conversion was 37%.

It can be seen that SSZ-58 has very high cracking activity, indicativeof strongly acidic sites. The low value of the Constraint Index and thefouling rate of SSZ-58 are typical of a large pore zeolite. In addition,the low fouling rate indicates that this catalyst has a good stability.

Example 38 n-Hexadecane Cracking

The product of Example 17 is treated as in Examples 34 and 35. Then asample is slurried in water and the pH of the slurry adjusted to a pH of˜10 with dilute ammonium hydroxide. To the slurry is added a solution ofPd(NH₃)₄(NO₃)₂ at a concentration which would provide 0.5 wt. % Pd withrespect to the dry weight of the zeolite sample. This slurry is left tostand at room temperature for 72 hours. Then, the slurry is filteredthrough a fritted glass funnel, washed with de-ionized water, and driedat 120° C. for two hours. The catalyst is then calcined slowly up to482° C. in air and held there for three hours.

The calcined catalyst is pelletized in a Carver Press and crushed toyield particles with a {fraction (20/40)} mesh size range. 0.5 gm of thecatalyst is packed into a ¼″ OD tubing reactor in a micro unit forn-hexadecane hydroconversion. Table III gives the run conditions and theproducts data for the hydrocracking test on n-hexadecane. After thecatalyst is tested with n-hexadecane, it is titrated using a solution ofbutyl amine in hexane. The temperature is increased and the conversionand product data evaluated again under titrated conditions. The resultsshown in Table III show that SSZ-58 is an effective hydrocrackingcatalyst.

TABLE III Temperature 534° F. 582° F. Time-on-Stream (hrs.) 33.8-45.757.7-70.2 WHSV 1.55 1.55 PSIG 1200 1200 Titrated? No Yes n-16, %Conversion 97.7 99.4 Hydrocracking Conversion, % 70.1 79.6 IsomerizationSelectivity, % 29.4 24.4 Crack. Selectivity, % 70.6 78.1 C₄, % 8.4 8.6C₅/C₄ 7.4 7.9 C₅+C₆/C₅, % 25.8 28.3 DMB/MP 0.04 0.04 C₄-C₁₃ I/N 1.64 2.1

Example 39 Nitrogen Adsorption

The product of Example 2 is treated as in Examples 34 and 35. Then it issubjected to a surface area and micropore volume analysis using N₂ asadsorbate and via the BET method. The BET area is 326 m²/gm. Theexternal surface area of the zeolite is 88 m²/gm and the microporevolume is 0.11 cc/gm.

Example 40

Using a procedure similar to that of Example 2, SSZ-58 is prepared usinga N-propyl-cyclooctylpyrrolidinium cation (Template B) as the templatingagent.

What is claimed is:
 1. In a process for the reduction of oxides ofnitrogen contained in a gas stream in the presence of oxygen whereinsaid process comprises contacting the gas stream with a zeolite, theimprovement comprising using as the zeolite a zeolite having a moleratio greater than about 20 of an oxide of a first tetravalent elementto an oxide of a second tetravalent element which is different from saidfirst tetravalent element, trivalent element, pentavalent element ormixture thereof and having, after calcination, the X-ray diffractionlines of Table II.
 2. The process of claim 1 wherein said zeolitecontains a metal or metal ions capable of catalyzing the reduction ofthe oxides of nitrogen.
 3. The process of claim 2 wherein the metal iscopper, cobalt or mixtures thereof.
 4. The process of claim 2 whereinthe gas stream is the exhaust stream of an internal combustion engine.